The present invention generally relates to wire cutters and, more specifically, to those wire cutters having the ability to cut a wire flush to an adjacent surface or element and the ability to hold the cut off segment of wire.
Wire cutters are currently available in many different forms. Typically, wire cutters have a pair of pivotably connected, plier style handles connected to respective pairs of cutting jaws. The jaws have cutting surfaces which may comprise two sharp edges which either meet in abutting relationship or interact in a scissor-like fashion. If the cutting surfaces abut one another to cut a wire, one of the surfaces may simply be a flat anvil surface against which an opposing sharp cutting edge interacts to cut the wire.
In certain applications, such as in the orthodontic field, it is necessary not only to cut a section of wire, but also to hold the cut off segment to prevent that segment from ejecting or falling into the mouth of a patient. One orthodontic application in which this feature is desirable involves the distal end of an archwire in an orthodontic appliance. The archwire typically extends through a buccal tube at this location and a segment of wire may project outwardly from an end of the tube for various reasons. This segment of the archwire is ideally cut flush to the end of the buccal tube during installation of the appliance. Wire cutting may also be required during maintenance or adjustment procedures. In this regard, once an archwire has been attached to an orthodontic appliance in the mouth of a patient, various movements of the appliance often take place over time. During these movements, the archwire may "walk" or move through the brackets of the orthodontic appliance. This may cause the end of the archwire to again be exposed from the end of the buccal tube. The exposed wire segment may cause irritation to the surrounding mouth tissue of the patient. For this purpose, specifically designed wire cutters have developed, with some including a flush cut and/or holding ability. Wire cutters having a scissor-type action do not generally enable a flush cut to the buccal tube. Therefore, to enable a flush cutting and holding ability, wire cutters having a sharp edge on one jaw and an anvil on the other or those having various forms of abutting cutting edges have been the options of choice.
Certain orthodontic distal end cutters currently available include a cylindrical spring holding wire attached to a jaw having a sharp cutting edge. A clipped wire segment is meant to be held between the cylindrical spring holding wire and an opposing jaw after the wire is cut. This type of wire cutter may specifically be referred to as a distal end cutter having a flush cut and hold feature. The spring holding wire associated with these distal end cutters has certain significant disadvantages. First, because it is cylindrical in shape, the contact that the spring holding wire makes with the cut segment of the archwire is not directly adjacent to the cutting surface, but is displaced at least by the radius of the spring holding wire. Therefore, in the case of certain short segments of archwire extending from a buccal tube, for example, the cut off segment may not extend fully to the contact point of the spring wire. Since adequate contact may not be made between the spring holding wire and the archwire segment, the archwire segment may not be held firmly in place between the jaws. This archwire segment may therefore drop or eject into the mouth of the patient.
Moreover, spring holding wires have been connected to distal end cutters of the type that include a sharp cutting edge on one jaw and a flat anvil surface on the opposite jaw. In currently available devices, the spring holding wire has been connected adjacent to the sharp cutting edge such that it bears against the anvil surface during a cutting operation. As the jaws are moved together to cut an archwire, the spring holding wire moves laterally away from the cutting edge and generally along the axis of the archwire. Therefore, it may also move away from the end of the clipped archwire segment. This tends to lead to the same holding problems discussed above. Also, due to its circular cross section, a cylindrical spring holding wire will only make point contact with an archwire segment that also has a circular cross section. This may not supply enough gripping contact to keep the archwire segment from being ejected into a patient's mouth. Finally, distal end cutters, such as described above, have not had the ability to cut a relatively wide range of wire diameters, constructions and cross sections. Instead, users have to resort to a larger or smaller wire cutter.
For at least the reasons stated above, it would be desirable to provide a wire cutter, and more specifically an orthodontic distal end cutter, having the ability to cut very short segments of wire flush to the end of a buccal tube while also holding the clipped wire segment. It would also be desirable to provide such a wire cutter having the ability to cut a relatively wide range of wire diameters, constructions and cross sections.